Oven door with self-contained counter-balancing means



Aug. 2, 1966 A. J. MACAULAY 3,263, 674

OVEN DOOR WITH SELF-CONTAINED COUNTER-BALANCING MEANS Filed Dec. 9, 1964 2 Sheets-Sheet 2 ZS I INVENTOR AUGus I MAcAv M! BY WK pus ATTORTOEQ United States Patent 3,263,674 OVEN DOOR WITH SELF-CONTAINED COUNTER-BALANCING MEANS Angus J. Macaulay, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Dec. 9, 1964, Ser. No. 417,141 Claims. (Cl. 126-191) The present invention relates to the art of counterbalanced doors, and particularly a self-contained counterbalancing means utilizing torsion springs for a front-opening drop door of a kitchen appliance such as a domestic oven or automatic dishwasher. However, this invention will be described with relation to a domestic oven as it was specifically designed for such use and it appears to have its greatest utility in that art.

Some models of domestic ovens have been provided with easily removable oven doors for approximately the last decade. Such oven doors facilitate the ease of cleaning the oven by making it possible for the housewife to reach all points of the oven cavity once the door is removed. In recent times, the housewise has also been given a choice between several types of oven doors for the same model range. The door may be a plain solid door, or one with a window, or one with special decorative treatment, as well as having mix-or-match colors to blend with other appliances in the kitchen or with the kitchen cabinets. Also, there is a movement afoot to ship the oven from the factory minus the oven door, and to ship the doors separately to the dealer in quantity who will install the one chosen by the purchaser at the time of purchase. It will be appreciated that all of these various door designs will not have the same weight for a particular door size. The weight will vary depending upon the type of accessories provided with each particular door. This variation in weights creates a problem in providing a single door counter-balancing means built into the oven body, and which will be satisfactory for any one of the possible door choices. The answer to this problem has been solved by the present invention by building the door counter-balancing means into each oven door, rather than having such means built into the oven body as heretofore.

The principal object of the present invention is to provide a swinging door with an adjustable, self-contained door counter-balancing system so that the same system can be utilized for the various sizes and weights of doors.

A further object of the present invention is to provide a swinging door with a self-contained counter-balancing system utilizing an adjustable torsion bar system.

A further object of the present invention is to provide aswinging door with a self-contained torsion bar counterbalancing system and latch means for immobilizing the torsion bar so as to facilitate the removal of the door from the door frame.

A further object of the present invention is to provide a torsion bar counter-balancing system of the class described with adjustable means for the torsion bars capable of varying both the angularity and the effective length of the torsion bar in order to render the bar usable on doors of dilferent weight-s.

The present invention, in accordance with one form thereof, is embodied in a hinged door that is capable of swinging between a vertical closed position and a substantially horizontal fully open position. Counterbalancing means is provided for the door to retard the opening action of the door as it moves away from its vertical position, as well as to facilitate the closing action of the door as it moves towards the vertical position. The counter-balancing means comprises a torsion bar means and a hinge lever means, where the lever means is connected to one end of the torsion bar means ad- 3,263,674 Patented August 2, 1966 jacent a side edge of the door. The hinge lever means projects outwardly of the door in a plane generally perpendicular to the inner surface of the door. The door frame includes a low friction bearing surface which is adapted to be engaged at all times by an. edge of the hinge lever means due to the turning action of the torsion bar. The torsion bar means is provided with a support means within the door such that as the door is being opened the bearing surface deflects the hinge lever means in a direction opposed to the normal biasing force of the torsion bar means. The support means for the torsion bar means is made adjustable to render it possible to vary the axial position of the torsion bar means and thereby adjust the relative angle between the hinge lever means and the inner surface of the door. Another modification is a second direction of adjustability of the support means for varying the effective length of the torsion bar means. Also, an adjustable latch means may be utilized for engagement with the hinge lever means when the door is in a predetermined position for immobilizing the torsion bar means and facilitating the removal of the door from the door frame or oven body.

My invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIGURE 1 is a front elevational view of an appliance such as a domestic oven showing a front-opening access door with parts broken away to illustrate a self-contained door counter-balancing system utilizing a torsion bar means embodying the present invention.

FIGURE 2 is a fragmentary right side view partly in cross-section of the front portion of the oven taken on the line 22 of FIGURE 1 and showing the interaction between the hinge lever and a roller bearing on the door frame for exerting a holding force on the door while it is in the closed position.

FIGURE 3 is a fragmentary view similar to that of FIGURE 2 with the oven door moved to its substantially horizontal fully open position and showing a latch member engaging the hinge lever to immobilize the counterbalancing system.

FIGURE 4 is a fragmentary right side view of the adjusting means for the lower torsion bar taken on the line 4-4 of FIGURE 1.

FIGURE 5 is a fragmentary right side view similar to that of FIGURE 4 showing the adjusting means for the upper torsion bar and taken on the line 5-5 of FIG- URE 1.

FIGURE 6 is a fragmentary view of the detent means for the handle of the latch pin which is capable of im mobilizing the counter-balancing system.

Turning now to a consideration of the drawings, and in particular to FIGURE 1, there is shown for illustrative purposes an electric range 10 having a top cooking surface or cooktop 11 with a plurality of surface heating elements 12, and an oven 13 located beneath the cooktop 11 for performing both baking and broiling liner 15 which has a front opening that is adapted to be closed by an oven door 14. This door 14 is a frontopening, drop door that has a door handle 16 adjacent its top edge, and quick-connect hinge means 17 along its bottom edge. Looking at FIGURE 2, the hinge means 17 is shown as including a hinge bracket 18 that is fastened at its inner end 19 to a door frame 24 of the oven body and extends outwardly of the body through a suitable slot 20 formed in the front wall of the door frame. The outermost end of the hinge bracket 18 is formed with a hook member 21 that establishes an upwardly-facing slot 22 for receiving a hinge pin 23 that is mounted on the lower portion of the door 14 as is best seen in FIGURE 1. Thus, it will be seen that it is possible, at this stage of the design, to lift the hinge pin 23 of the door 14 in and out of the slot 22 of the hinge bracket 18, but that in the absence of this lifting force the door will remain connected to the oven by this quickconnect hinging means 17.

The two main elements of the door counter-balancing means are a torsion bar 25, as best seen in FIGURE 1, and a hinge lever 26 supported in cantilever fashion as is best seen in FIGURE 2. In actual practice the torsion bar 25 and hinge lever 26 is duplicated on the other side of the oven door 14; for example, by torsion bar 25' and hinge lever 26'. It is conceivable under certain circumstances that a single counter-balance system would suffice using only one torsion bar and one hinge lever, but the preferred embodiment of the present invention utilizes duplicate biasing means on each side of the door. Notice that the torsion bar 25 is of non-circular crosssection, or at least the ends thereof. In the illustrated embodiment it is of square cross-section. The supported end of the hinge lever 46 is fastened to the end of the torsion bar 25 as best seen in FIGURES l and 2. A slot 28 is formed in the inner panel of the door so that the hinge lever may project from the door in a plane that lies substantially perpendicular to the inner surface of the door.

The oven door 14 is made up of two dished panels;

namely, an outer panel 30 and an inner panel 31 as is best seen in FIGURE 4. The outer panel 30 is of rather simple configuration, while the inner panel 31 has a large central, rectangular embossment 32 which is adapted to telescope within the door opening or throat ofthe oven liner 15. This large embossment 32 is filled with thermal insulation 33 such as fiberglass or the like so as to retain much of the heat generated within the oven cavity and prevent its escape from the oven to the kitchen. There is atab and slot connection 34 at the lower edge of the door between the outer panel 30 and the inner panel 31, while the top portion of the door is held together with fastening screws (not shown) that extend through the inner panel of the door and into the door handle 16 as is the general practice in this art. Looking at FIGURE 1, each door hinge pin 23 is supported from a vertical channel member 35 that is fastened to the inside surface of the inner door panel 31 as by welding or the like. Connected between the two horizontally spaced channel members 35 is a large channel member 36 of generally hat shape, as seen in FIGURE 4, having oppositely turned end flanges 37 which are fastened to the sides of the channel members 35 as by means of fastening screws 38. The two torsion bars 25 and 25' are positioned mainly within the large channel member 36. Support means must be provided for the end of the torsion bar 25 adjacent its connection with the hinge lever 26. Looking at FIGURE 1, the channel member 35 is provided with a rotatable bushing 40 of sound deadening material such as nylon or the like which has a square hole for receiving the torsion bar 25 therethrough as well as a cylindrical outer surface fitted into a circular opening in one flange 41 of the channel bracket 35. This bushing 40 is confined in the flange 41 by shoulders so that it will not slip out of place.

One end of the torsion bar 25 is pivotally supported in the door 14 by means of the bushing 40, while the opposite end 43 must be rigidly fastened to the door. Such a fastening means is provided by an adjusting member 44 of FIGURES 1 and that is adapted to be assembled within the channel member 36 as by means of its flanges 45 and fastening screws 46. A cam member 48 is captured within the adjusting member 44, and the torsion bar 25 is fitted to the cam member 48 and extends through the adjusting member 44 as is best seen in FIG- URE 5. The adjusting member 44 includes an elongated adjusting screw 43 which is threaded through the bottom wall thereof and operates to position a slider 50 which is held against the cam member 48 as at point 51. Hence, the turning of the screw 49 will shift the slider either toward or away from the cam member 48, and in so doing would make an axial adjustment of the torsion bar 25. A suitable opening 52 is formed through the bottom edge of the door 14 to permit a blade of a screw driver (not shown) to be inserted therethrough for engaging a slotted head of the adjusting screw 49. Moreover, a stop clamp 53 is slipped onto the torsion bar until it bears against the side of the adjusting member 44. The clamp carries a set screw which when tightened holds the clamp firmly in place. Thus, the torsion bar cannot slip away from the adjusting member.

The possibility of moving the adjusting member 44 longitudinally of the torsion bar is illustrated in dotted lines in FIGURE 1. Alternate screw holes are provided in the channel member 36 so as to shorten the effective length of the torsion bar 25 in the event this counterbalancing means is to be used on a heavier door where more torsion spring action would be needed. It will be understood that the shorter the effective length of the torsion bar the greater will be its biasing force.

The second torsion bar and hinge lever combination 25' and 26' respectively is also provided with an adjusting member 44 that is best shown in FIGURE 4. The main difierence between the two adjusting members 44 and 44' is that the slider 50 is longer than the corresponding slider 50'. The reason for this is that the torsion bar 25' is nearer the lower edge of the channel member 36 than is the other torsion bar 25, as may be clearly seen in FIGURE 1. Each adjusting member 44 and 44' is provided with an enlarged cut-out 42 to accommodate the extension of the alternate torsion bar therethrough as can be seen in both FIGURES 4 and 5.

Going back to FIGURE 2 for a discussion of the hinge lever 26, it is provided with a cam surface 53 along its top edge. The distal end of the hinge lever 26 is provided with a hook portion 54 for engagement with a sound absorbing roller 55 of nylon or the like material that is pivotally mounted on the door frame 24. However, a stop member may be added adjacent the roller to be engaged by the hinge lever hook 54 so as to relieve the roller of such a heavy strain. This hook member 54 serves as a stop means to limit the outward swinging action of the door 14 to a substantially horizontal fully open position as is best seen in FIGURE 3. This roller member 55 has an additional function; namely, to serve as a low friction bearing member in engagement with the cam surface 53 of the hinge lever 26 for deflecting the lever in a clockwise direction as the door is lowered from its vertical to its horizontal position so as to build up energy within the torsion bar which will be needed in assisting the raising of the door back from the horizontal to the vertical position. The cam surface 53 has two other principal portions; namely, a closing surface 56 and a broil-stop surface 57-58. The closing surface 56 cooperates with the roller 55 for exerting a holding force against the door in the closed position as is best seen in FIGURE 2. The broil-stop surface 57-58 forms a V-shaped notch in which the roller 55 may be temporarily seated to hold the door in a partially open position of about 15 angularity with respect to the oven front. This is designated as the broil position for allowing the free flow of room air through the oven cavity when the top heating element or broil element is energized at full wattage.

It is also'important for the housewife to be able to remove this door 14 without the use of special tools or without any mechanical complications. This function is provided by a releasable latch pin 60 as best seen in FIG- URES 1 and 3. The latch pin is sl-idable under the hinge lever 26 when the oven door 14 is in its substantially fully open position of FIGURE 3 so as to engage behind a shoulder 61 of the lever and thereby immobilize the torsion bar 25. When this is done it is possible to partially close the door 14 and in so doing the hinge lever 26 will shift away from engagement with the roller 55. Thus the door may be lifted bodily from the hinge brackets 18. The releasable latch pin 60 is provided with a handle portion 63 which allows the manipulation of the latch pin.

As is best seen in FIGURE 3, a suitable tension spring 64 is connected at one end to the latch pin 60 as at 6'5, and is connected at its opposite end to an inner flange 66 of the door by means of a hook portion 67'. The reason for having the tension spring 64 is because the handle 63 cooperates with a pair of detent slots 68 in the inner panel 31 as is seen in FIGURE 6. Hence, the handle 63 of the latch pin 60 cannot be shifted from one extreme position to the other except by removal of the handle 63 from its detent slot against a biasing force provided 'by the tension spring 64, as will be understood by those skilled in this art.

, Modifications of this invention will occur to those skilled in this art, therefore, it is to be understood that this invention is not limited to the particular embodiments disclosed, but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An oven assembly having walls defining an oven cavity that has an opening in a front wall thereof, and a door for closing the said opening, hinge means adjacent the bottom edge of the door for removably securing said door to the front wall for swinging movement between a vertical closed position and a substantially horizontal open position, counter-balance means for the door including at least one hinge lever having a pivotal support means on the door adjacent one side edge thereof and lying in a plane that extends generally perpendicular thereto, a roller means mounted adjacent the front wall of the oven for engagement by the hinge lever, and a torsion bar within the door and fastened at one end to the hinge lever and serving as the said pivotal support means for the lever, and a point adjacent the opposite end of the torsion =bar being fastened to the door so that an opening movement of the door exerts a twisting force on the torsion bar by the act of the roller deflecting the hinge lever.

2. An oven assembly having walls defining an oven cavity that has an opening in a front wall thereof, and a door for closing the said opening, hinge means adjacent the bottom edge of the door for securing said door to the front wall for swinging movement between the vertical closed position and a substantially horizontal open position, door counter balancing means comprising hinge lever means attached to the door adjacent the side thereof and lying in a plane generally perpendicular thereto, a bearing surface adjacent the front wall of the oven for engagement by the hinge lever, and a torsion bar means located within the door and having one end fastened to the hinge lever and a point adjacent the opposite end of the torsion bar rigidly attached to the door, whereby an opening movement of the door exerts a twisting force on the torsion bar means by the action of the hinge lever being deflected by the bearing surface.

-3. An oven assembly having walls defining an oven cavity that has an opening in a front wall thereof, and a door for closing the said opening, hinge means adjacent the bottom edge of the door for securing said door to the front wall for swinging movement between a vertical closed position and a substantially horizontal open position, door counter-balancing means comprising a torsion bar means located within the door and having a point adjacent one end thereof rigidly fastened to the door, a bearing means on the door adjacent the opposite end of the torsion bar means for rotatably supporting the torsion bar means, and a hinge lever means attached to the said opposite end of the torsionbar means and lying in a plane generally perpendicular to the inner surface of the door, and a bearing surface adjacent the front wall of the oven for engagement by the hinge lever, whereby an opening movement of the door exerts a twisting force on the torsion bar means by the action of the hinge lever means being deflected by the latter bearing surface.

4. A structure having a vertical wall with a door open ing therein, a door adapted to close said opening, hinge means adjacent the bottom edge of the door for securing the door to the wall for swinging movement between a vertical closed position and a substantially horizontal open position, door counter-balancing means comprising a pair of torsion bars located within the door generally parallel with the pivotal axis of the hinge means, one end of each bar being located adjacent a side edge of the door, the door having a rotatable support means for each bar adjacent said one end of each bar, a point adjacent the opposite end of each bar being fastened to the door, a hinge lever attached to the said one end of each bar and lying in a plane generally perpendicular to the inner surface of the door, a roller surface on the said 'wall at each side of the door opening, each torsion bar serving as a biasing force to hold its hinge lever in engagement with the related roller surface, whereby an opening movement of the door energizes the torsion bars by the interaction of the hinge levers being deflected by the roller surfaces.

5. A structure as recited in claim 4 with adjustable means located at each point where the said opposite end of each torsion bar is fastened to the door, each of said adjustable means being capable of twisting the related torsion bar about its longitudinal axis so as to set the proper angle of the hinge lever with respect to the inner surface of the door.

6. A structure as recited in claim 5 wherein the said adjustable means for each torsion bar may be positioned at varying locations along the length of the torsion bar so as to vary the biasing spring force of the bars to compensate for doors of different weights.

7. A removable door structure, a body having a vertical wall with a door opening therein, a pivoted door adapted to close said opening, a pair of first hinge members rigidly secured to said body at the bottom edge of the opening, a pair of second hinge members carried by the lower edge of the door and adapted to engage with the first pair of hinge members and serve as quick release pin and slot hinge mean-s for the door, counter-balancing means for the door comprising a torsion bar means located within the door and having a rotatable support means adjacent the side edge of the door, a hinge lever fastened to the end of the bar means adjacent the said support means, and an adjustable mounting means adjacent the opposite end of the bar means for fastening the bar means to the door, said mounting means being capable of adjustment both longitudinally and axially of the bar means, the hinge lever being biased into engagement with the Vertical Wall, said biasing force being increased by the deflection of the hinge lever as the door moves from a vertical toward a horizontal position.

8. A removable door structure as recited in claim 7 with the addition of an adjustable latch means carried by the door and engageable with the hinge lever to immobilize the torsion bar means to facilitate the separation of the hinge means and the removal of the door.

9. A door structure, a door frame defining an opening that is to be closed by the door, quick-connect hinge means adjacent the bottom edge of the door for removably securing said door to the door frame for swinging movement between a vertical closed position and a substantially horizontal open position, counter-balance means for the door including torsion bar means located within the door, and hinge lever means connected to one end of the torsion bar means adjacent the side of the door and located within a plane that is perpendicular to the inner surface of the door, a low friction bearing located adjacent the door frame, the top surface of the hinge lever means being formed with a cam surface that is biased by the torsion bar means into engagement With the hearing at all times, the door including a rotatable bearing adjacent the hinge lever means for receiving the torsion bar means therethrough, the door also including an adjustable fastening means that is engageable with the torsion bar means remote from the hinge lever for setting the angle of the hinge lever with respect to the door and holding the torsion bar means firmly in place.

10. A removable door structure, a door frame defining an opening that is to be closed by the door, a quickconnect hinge means adjacent the bottom edge of the door for removably securing said door to the door frame with swinging movement between the vertical closed position and a substantially horizontal open position, counterbalance means for the door including a pair of torsion bars, each bar supporting a hinge lever adjacent one end, each hinge lever extending in cantilever fashion outside the door and lying in a plane at the side of the door that the door frame, each hinge lever having a cam surface,

on its top edge that is biased into engagement with one of the rollers by the spring action of the related torsion bar, the door including an adjustable means for each torsion bar adjacent the end remote from the hinge lever for varying the relative angle of the hinge lever with respect to the inner surface of the door, the door also being provided with an adjustable latch at each side of the door for engagememt with the adjacent hinge lever when the door is, in its substantially horizontal fully open position for immobilizing the torsion bar for removal of the door.

References Cited by the Examiner UNITED STATES PATENTS 2,539,151 1/1951 Mills 126-194 2,894,277 7/1959 Bogater et a1. 16-180 3,067,453 12/1962 Lyons 16-180 3,123,064 3/1964 Hartson 126191 KENNETH W. SPRAGUE, Primary Examiner. 

1. AN OVEN ASSEMBLY HAVING WALLS DEFINING AN OVEN CAVITY THAT HAS AN OPENING IN A FRONT WALL THEREOF, AND A DOOR FOR CLOSING THE SAID OPENING, HINGE MEANS ADJACENT THE BOTTOM EDGE OF THE DOOR FOR REMOVABLY SECURING SAID DOOR TO THE FRONT WALL FOR SWINGING MOVEMENT BETWEEN A VERTICAL CLOSED POSITION AND A SUBSTANTIALLY HORIZONTAL OPEN POSITION, COUNTER-BALANCE MEANS FOR THE DOOR INCLUDING AT LEAST ONE HINGE LEVER HAVING A PIVOTAL SUPPORT MEANS ON THE DOOR ADJACENT ONE SIDE EDGE THEREOF AND LYING IN A PLANE THAT EXTENDS GENERALLY PERPENDICULAR THERETO, A ROLLER MEANS MOUNTED ADJACENT THE FRONT WALL OF THE OVEN FOR ENGAGEMENT BY THE HINGE LEVER, AND A TORSION BAR WITHIN THE DOOR AND FASTENED AT ONE END TO THE HINGE LEVER AND SERVING AS THE SAID PIVOTAL SUPPORT MEANS FOR THE LEVER, AND A POINT ADJACENT THE OPPOSITE END OF THE TORSION BAR BEING FASTENED TO THE DOOR SO THAT AN OPENING MOVEMENT OF THE DOOR EXERTS A TWISTING FORCE ON THE TORSION BAR BY THE ACT OF THE ROLLER DEFLECTING THE HINGE LEVER. 